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AdministeringIn addition to administering the database server, you can tune performance, replicate data, and archive data.
System administrationThese topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL OneDB™ database servers.
Performance GuideThe HCL OneDB™ Performance Guide describes how to configure and operate your HCL OneDB™ database server to improve overall system throughput and to improve the performance of SQL queries.
Table performance considerationsSome performance issues are associated with unfragmented tables and table fragments.
Managing extentsAs you add rows to a table, the database server allocates disk space in units called extents. Each extent is a block of physically contiguous pages from the dbspace. Even when the dbspace includes more than one chunk, each extent is allocated entirely within a single chunk, so that it remains contiguous.
Monitoring the upper limit on extents and extent interleavingYou can monitor the upper limit on the number of extents. You can also check for and eliminate extent interleaving.
Eliminating interleaved extentsYou can eliminate interleaved extents by reorganizing the tables with the UNLOAD and LOAD statements, creating or altering an index to cluster, or using the ALTER TABLE statement.
Using ALTER TABLE to eliminate extent interleaving If you use the ALTER TABLE statement to add or drop a column or to change the data type of a column, the database server copies and reconstructs the table. When the database server reconstructs the entire table, it rewrites the table to other areas of the dbspace. However, if other tables are in the dbspace, no guarantee exists that the new extents will be adjacent to each other.

Using ALTER TABLE to eliminate extent interleaving

If you use the ALTER TABLE statement to add or drop a column or to change the data type of a column, the database server copies and reconstructs the table. When the database server reconstructs the entire table, it rewrites the table to other areas of the dbspace. However, if other tables are in the dbspace, no guarantee exists that the new extents will be adjacent to each other.

Important: For certain types of operations that you specify in the ADD, DROP, and MODIFY clauses, the database server does not copy and reconstruct the table during the ALTER TABLE operation. In these cases, the database server uses an in-place alter algorithm to modify each row when it is updated (rather than during the ALTER TABLE operation). For more information about the conditions for this in-place alter algorithm, see In-place alter.